@buddhasummer has some great pics of the differences in the first post on page 15 (post #141).
It was replied to with this:
If you send me a sample of the jam nut for the G250 I’ll see if I can have it made with wrench flats.
Which is why I thought we were still discussing the standard G250. @Open Ocean Diver which model are we having this nut manufactured for?
TIA